Minecraft crashed after opening a minecraft singleplayer-world

1. i opend minecraft pushed the singleplayer button
2. i selected a minecraft world (the world isnt unstable (its not the world fault >:L ))
3. then i pushed the play button
4. after a unusual long loading time Minecraft crashed (i have rly expensive gaming pc, its not a pervormans issue)
5. i cried xD

and also all servers are unavaiable and when i try to connect to 1 i get the java error: java.lang.nullpointerexception: group

because of the serverproblem i reinstalled java and minecraft (and still had the same problem)